Volume control in sound record reproduction



Oct. 20, 1931. J. R. BALSLEY V VOLUME CONTROL IN SOUND RECORDREPRODUCTION 1929 4 Sheets-Sheet Fi ed Oct. 14,

Inventor Jamsflflalsley,

flttorncy Oct. 20, 1931. J. R. BALSLEY VOLUME CONTROL IN SOUND RECORDREPRODUCTION Filed Oct. 14, 1929 4 Sheets-Sheet 2 Jrzuvzior James 15'.Balsley.

flttorlzey.

Oct. 20, 1931. J. R. BA'LSLEY 1,827,735

VOLUME CONTROL IN SOUND RECORD REPRODUCTION Filed Oct. 14, 1929 4Sheets-Sheet 3 c 109 I n I II I I l 4 I I I E E a 1722012102 JamesREaZJl ey,

Oct. 20, 1931.

VOLUME J. R. BALSLEY 1,827,735

CONTROL IN SOUND RECORD REPRODUCTION Filed Oct. 14, 1929 4 Sheets-Sheet4 I m/enZor Jarrwskflalslqy.

Patented Oct. 20, 1931 UNITED STATES PATENT, OFFICE JAMES a. rust, orBEVERLY 'rrrLLs, camromwm, assrenoa 'ro rox mu con.-

roaa'rron, or nonmrwoon, cmronm, a comom'rrox or m You 'VOIlIJ'MECONTROL IN SOUND RECORD BIEPBODUUIION Application filed October 14,1928. Serial No. 898,464.

' I i This invention relates generally to the reproduction ofsound fromsound records, and is -more particularly concerned with means forcontrolling the volume of sound reproduced from sound records. Theinvens tion is particularly applicable to systems in which thephotographic type of sound records are utilized, and will therefore behereinafter described with that type of sound record chiefly in View;but it will readily be understood that this particulariza-tionconstitutes no limitation on the invention, for the invention may alsobe practiced in connection with other types of sound records such as themechanical disk type.

In sound reproduction from photographic sound records of the varyingwidth type, the volume of the reproduced sound is proportional ,to theamplitude of the serrations along the record. The volume ran e of thereproduced sound is limited on t e lower side by ground noise, and onthe upper side by the physical characteristics of the film and theelectrical and mechanical limitations of the system. In reproductionfrom photographic records of the varyin density type,

the volume of the reproduce sound is pro-- portional to the change intransmission of the sound record. In the latter system the practicalvolume range is limited for undistorted quality by the length of thestraight line portion of the light-transmission characteristic of thefilm,and is further limited on on the lower side by the ground noiselevel of the film, and on the upper side by the physical characteristicsof the film, plus the electrical and mechanical limitations of therecording and reproducing units.

Corresponding factors similarily limit the practical available volumerange in sound reproduction systems utilizing other types of soundrecords. I

It is a primary object of the present invention to provide means forexpanding the pracprovide means whereby the volume of sound in finalaudible reproduction from a sound record may be controlled atpredetermined levels, irrespective of the levels at which the soundwasoriginally recorded.

According to the present invention, these obg'ects are accom lished bythe provision of a volume-control record driven in synchronism with" thesound record, and adapted to control the volume level of the soundreproduced from the sound record. In my preferred emblodimelnt thisvoluntiie controllr ecord m'ay simp ya varyin ensit otographic record,which may be pre lu led by reference to the volume level 'of t e soundrecord as recorded, as'may be determined by ordinary reproductionthereof. This volume control record, which may be printed on the samefilm that carries the pictures and sound record, for instance outsidethe sprocket perforations thereof, or on a separate film if moreconvenient, is o erated in conjunction with a light beam andphotoelectric cell to produce a varying electrical current which isutilized tocontrol the level of reproduction, and to do thisirrespective of the level at which the sound record was recorded.

With the foregoing in mind, the invention will best be understood fromthe following detailed description of a present preferred embodimentthereof, reference for this purpose being had to the accompanying draw-1ngs,'in which: I

1 shows in diagrammatic form a system r producing a volume controlrecord on the same film that carries the sound record and pictures;

Fig. 2 shows a system in which the volume record and controllin thevolume thereof representing t The sound reproducing and soundcontroleeann fied reproduction of the original sound recnected to lead20 between condenser C and the 0rd; 1 L grid of tube 21, this lead andthe resistance R, Fi 3 shows a system for reproducin roviding for anegative bias on the grid. soun from aphotographic sound record an beoutput leads 27 and 28 of amplifier 22 controlling the volume levelthereof inacare shown connected to ausual speaker 29. cordance with thepresent invention; A photographic volume control record is Fi 4 shows asystem for reproducing made by reference to the volume level of thesound from a mechanical disk record an sound record 12, as hereinafterdescribed, controlling the volume level thereof by means this volumecontrol record eonsistin in the of a photographic volume control record;present case ofa varying density nd 30 yFig. showsa variational systemfor reprinted on film outsi e of the sprocket producing sound from aphotographic sound perforations 13,};md its variations in density t e inaccordance with t e present invention, changes deslred. A ight-slit 31is provided and- 4 before record 30, slit 31 being illuminated, Fig. 6shows another variatioual system forinstance, means. of an illuminant 32for reproducing sound. from a photographic and lens 33. sound-record andcontrolling the volume slit 31 strike'the record on film 10, and thethereo- 3n accordance with the present invenrays transmittedtherethrough, which, of course, are-proportional to the transmission ofthe record, impinge upon a photoelectric ling system, diagrammaticallyillustrated in cell 35 to generate an electrical current there- Fig. 3,will be described first, after which in inversely roportional to thedensity of wi 1 be explained how the volume controlling record 30. Potoelectric cell 35 is connected record .therein utilized can beprepared. by means of lead 36 and 37 directly across Referring thereforeto Fig. 3 the numeral the grid and plate of vacuum tube 38. In- 10indicates the moving sound-picture film cludedin the plate circuit 39 oftube 38 is having-thereon the usual pictures 11 and a'battery 40 and theresistance R, of lead sound record 12 between t e two rows of 26, andincluded in the grid circuit 41 of the sprocket perforations 13, asusual, and contube is a resistance R, and abattery 42. ventionallillustrated as driven by means The plate circuit 39 of tube 38 is soconof a sproc et 14. The re roducing elements nected with respect toresistance R, that for the sound record 12 include tygically a when tube38 has normal plate current (no. light-slit 15 located before the sounrecord, light on photoelectrical cell 35), the plate curan illuminant16, alens 17 for throwing light rent creates a dro across R, such as tooprays from illuminant lfi through slit 15 to pose the normal roptherein, and thus rethe sound record 12, and a photoelectric cell ducethe bias on .the grid-of tube 21 to such a 18 positioned to be impingedby the light rays value 11%;; amplification is at a m ximumwhich aretransmitted through the sound rec- When, ever, light impinges on cell35, a old. These trans ittd light rays a m llcurrent flows in leads 36and 37 which, when lated in Pas ing lgl' llgh he Soun recor the cell isconnected in the circuit withproper redetermined volume i 4 helight-rays passing through 0n the film by t sound-wave-representingregard topolarit reduces thdkpotential of the plate, and this in turncauses the plate is shown, the balance oft density variations thereon,and, striking the photo-electric cell, generate therein a varymgelectrical current corresponding to the onginal sound waves. One side ofthe photoelectric cell is grounded, as shown, whlle the other side isconnected by means of a lead 20 to the grid of the first tube 21 ofthevacuum tube amplifier, conventionall illustrated at 22. Only thefirst st e of t e am lifier e circuit belng of any suitable orwell-known't pe. A battery 25 is connected at one side t rouglraresistance R to lead 20 and at the-other side to ground, for the purposeof providing a conv is connecte at one side to the negative ter-' minalof the filament of tube 21, and at the other side to ground. A

gcrounded lead 26 having therein resistances A, condenser O is providedinilead 20 becurrent to be reduced, which accordingly allows the dropacross R, to increase. This causes an increased negative bias on thegrid,- which finally means a reduction of amplification, as is wellunderstood in the art.

It is possible to operate with the polarity of the photoelectriozcellreversed, in which case an increase in cell current operates to decreasethe drop across R and hence to increase the amplification of the system.In such" a case the system is, of course, so des1 tamed when there is nolig t on the cell.

The bias onthe grid of the amplifier tube ed that minimum am lificationis ob- 21,: and therefore the amplification of the Ill ofrecording orthe nature of the sound record by merely preparing and utilizing theproper volume control record.

The volume control record may be made in a system such as is illustratedin Fig. 1. As there illustrated, the traveling sound-picture film 10 isintercepted in a band outside its perforations 13 by alight beam castfrom an illuminated light-slit 46 by means of a lens 45, slit 46 beingilluminated b an incandescent lamp 47. Lamp 47 is lig ted by means of abattery 48, a variable-potentiometer 49 being included in the lightingcircuit for the purpose of varying the potential impressed upon the lampand hence the light intensity thereof and the density of the record 30printed on film 10. Potentiometer 49 may be regulated either manually inaccordance with predetermined data or automatically in accordance withpredetermined settings of suitable devices. The operation mayconveniently be carried on during the printing of either the pictures orthe sound record on the film 10, utilizing for this purpose devices andmethods similar to those now commonly employed for varying the intensityof the printin li ht as the changing scenes require.

n ig. 2 is shown a variational sys em for making the volume controlrecord. In this case the volume control record 30 is printed upon a film50 separate from the film 10a which carries the pictures 11 and soundrec" ord 12. 1 In this figure there is shown a system by which thevolume control record 30 can be made under manual control by an operatorwhile listening to a reproduction of the sound record 12 at the levelsof original recordin The films 10a and are conventionally illustrated assynchronously driven by sprockets 51 and 52 mounted on a driving shaft53, shaft 53 being driven by any convenient means, not shown. The soundrecord12 on film 10a is reproduced as audible sound in any usual manner,for instance, by means for an illuminant 54, lens 55, slit 56,photoelectric cell 57, amplifier 58 and speaker 59. An optical system isprovided for printing a varying density record on the moving film 50,and comprises typically an incandescent lamp 60, a slit 61 illuminatedthereby, and a lens 62 for casting an image of slit 61 on the movingfilm 50. A battery 65 is connected by means of circuit 66 with lamp 60,a variable potentiometer 67 being provided in the circuit for thepurpose of controlling the potential impressed on the lamp, and-hencethe intensity 5 of its light and the density of the volume record 30.The operation of this system is as follows: A trained operator listensto the reproduction of record 12, and simultaneously controls thevariable potentiometer 67, which governs the density of the volumecontrol record which is being produced. Knowing from experience how thesettings of potentiometer 67 govern the volume modifying characteristicsof the record 30 which he is producing, the operator is able to listento the sound reproduced by speaker 59 and simultaneousl set or controlhis potentiometer'67 in accor ance with the volume changes which hedesires to be finally effected, in such a way that in final reproductionthe volume control record which he has made will modify or control thevolume of the reproduced sound at the levels whichhe has thuspredetermined.

In Fig. 4 is shown a system for controlling volume level in reproductionfrom a sound record of the mechanical disk type. The mechanical diskrecord is shown at 104, and an electro-magnetic pick-up therefor at 105.One side of the pick-up is grounded, while the other side thereof isconnected by lead 106 to the grid of the first tube 107 of the vacuumtube amplifier, conventionally illustrated at 108. Only the first stageof the amplifier is shown, the balance of the ampli fying circuit beingof any suitable or well known type. The output leads 109 of theamplifier are connected to a speaker unit 110,

as usual. The negative terminal of the filament of amplifier tube 107 isconnected ,through a resistance It to ground, and a condenser C isincluded in lead 106. A lead 111 having therein resistances R and R iscon nected to lead 106 between condenser C and the grid of tube 107.

Themoving film 112 having thereon the volume control record 113 ispassed before the photoelectric cell 35, and an optical systemconsisting of an illuminant 32, lens 33 and a light-slit '31 is utilizedto transmit light rays throu h record 113 to impinge upon photoelectriccell 35. Cell 35 is connected across the grid and plate of a vacuum tube38, the plate circuit 39 of which include the resistance R fand the gridcircuit of which include a resistance R,. The operation of the volumecontrolling portion of this system is identical with that of the systemsillustrated in Fig. 3, and will be understood without furtherexplanation.

Various other schemes for controlling the volume level of reproducedsound in accordance, :with an electrical current produced from a volumecontrol record are possible. For instance, as illustrated in Fig. 5, theproperty of a photoelectric cell by virtue of which its sensitivityvaries in accordance with the applied potential, may be utilized to thisend. The system illustrated in Fig. 5 has the film 10 with its soundrecord 12 and optical system therefor 15, 16, 17, and also with thevolume control record 30 and optical system '31. 32, 33, all similar tothe previously described system of Fig. 3. Here, however. one side ofthe photoelectric cell 70, provided for sound record 12, is connected bymeans of lead 71 to the grid of the first tube 72 of the vacuum tubeamplifier, conventionally illustrated at 73. The other side of the cellis connected Ill by lead 74 to a battery 75, and the other side of thebattery is connected by lead 7 6 to lead 71, lead 76 having thereinresistances R, and

R and being grounded between the two re- 'sistances, as shown. Theoutput leads 77 of the amplifier are connected to a usual speaker 78. Acondenser G is located in lead 71 between the connection therewith oflead 76 Photoelectric cell 80, in which is generated an electromotiveforce proportional to the volume control record 30, is connected'byleads 81 and 82 with the grid and Flate/respectively of the vacuum tube83. he plate circuit 84 of the-tube-83 includes the resistance R,,- audthe grid circuit 85 thereof in cludes a resistance R The connections ofthe circuit may be made to such that an increase in the hotoelectriccell current in circuit 81, 82 Wlll cause either an increase or adecrease in the drop across resistance R de pending merely upon thepolarit of various connections of the circuit, as wi 1 be understood. Ifthe system is so arranged that an increase in photoelectric cell currentwill cause an increased drop across resistance R,, then the constants ofthe system will be so balanced that with no light on photoelectric cell80, and hence a minimum drop across resistance R,, a maximum potentialwill 'be impressed by battery 75 across photoelectric 85 cell 70. Thesensitivity of photoelectric cell 70, and hence the volume level ofreproduction, will then be at a maximum. When, however, cell 80 isimpinged upon by a beam of light the drop across resistance R, isincreased and the potential applied to cell '70 correspondinglydecreased, to the end that the sensitivity of cell and hence the volumelevel of reproduction are correspondingly lowered. If, on the otherhand, the conneci 45 tions are so arranged that an increase in thephotoelectric cell current in circuit 81, 82 causes a decrease in thedrop'across resistance R then the sensitivity of cell 70, andcorrespondin ly the volume level of re rol0 duction, will e at a maximumwhen the light impinging on cell. is at a maximum, and

a decrease in the light impinging on cell 80 will produce a decrease inthe volume of reproduction, as will be understood. 1

6 In Fig. 6 is shown'a system for controlling the :amplifier' by meansof a screen grid. Here again, the film 10 with its sound record 12 andoptical system 15, 16,17, and also with the volume control record 30 andop- I! tical system 31, 32, 33, are similar to the system, of Fig. 3.The photoelectric cell for sound record 12 is grounded at one side, and

is connected at its other side by lead 91 to the grid of the first tube92 of the vacuum tube I amplifier. conventionally illustrated at 93.

ground noise can be made relatively The filament of tube 92 is connectedby lead 94 to und, and also to battery 95,1418 other side 0 which isconnected through resistance R to the grid of the tube; A screen grid 96provided 1n'tube"92 is connected b a lead 97 to one side ofv a battery98 and e other side of battery 98 is connected to one side of aresistance the other side of which ia connected to ound, as indicated.Resistance lit is inc uded in the plate circuit 99 of a vacuum tube 100,across the grid and plate elements of which are connected leads 101 ifrom a photoelectric cell 102 provided for the volume control record 30on film 10. The

output leads 103 of amplifier 93 are connected to a usual speaker unit104.

The light transmitted through volume control record 30 affects thephotoelectric cell 102 to generate a proportional current therein, whichcurrent acts upon the vacuum tubev circuit to vary the drop acrossresistance R; p

in the platecircuit 99. Variation of the drop across R, then varies thepotential on the the amplification is in exact direct proportion to thepotential applied to the screen grid, and the volume control thereforefollows a straight line characteristic. 7

From what'has now been said, it will be recognized that'the invention inall of its described .forms provides means for greatly enlarging thepracticable volume range in reproduction of sound records, whatever maybe the nature or characteristics of thesound records utilized. Inanother aspect, it provides for the adjustment or modification of thelevel of reproduction of the original sound record. 4

- An advantage in the use of the present invention resides in thepossibility of reducing ground noise to negligible roportions. Groundnoise is only audible or o jectionable when the ratio of-recorded soundto ground noise is low. Therefore, by merely recording all sound athigher than usual levels and re ucin these levels in reproductionaccording to the methods of the present invention, so small as to beentirely negligible. v

The system will in many cases eliminate the necessity for retakes, whichare now often required for the reason that when a picture is completedit is found that certain scenes must be rejected because they arerecorded at an improper level to match up with the balance of thepicture. The application of the present'invention to such a situation isobvious.

In general, the system thus provides for the correction or adjustment ofvolume level 'after the picture is completed. And in addition it makesreproduction possible at both higher and lower levels than haveheretofore been consistent with substantially perfect or acceptablereproduction.

It will be recognized that the illustrative systems specificallydescribed herein are capable of considerable modification andrearrangement without departing from the spirit and scopeof m invention;and it is therefore to be un erstood that the following claims embraceall such' modifications and equivalent arrangements as may fairly beconstrued to fall within the scope of my invention. j

I claim:

1. In combination with a system for reproducing sound waves from a soundrecord, which system includes means for driving the sound record, meansfor producing from the sound record varying electrical current wavescorrespondin to the sound waves, and means for reproducing sound fromsaid current waves; a volume control record moved synchronously with thesound record, means for producing from the volume control recordelectrical currents corresponding to volume variations recorded thereon,a vacuum tube and a circuit therefor, leads connecting the varyingelectrical current produced from the volume control record across thegrid and plate of said vacuum tube, whereby a varying piate currentcorresponding thereto appears in the plate circuit of the tube, andmeans for modifying the volume level of the reproduced sound inaccordance with the variations in said plate current.

2. In a system for reproducing sound waves from a sound record, meansfor driving the sound record, means for producing from the sound recordvarying electrical current waves corresponding to the sound waves, avacuum tube amplifier for amplifying said current waves, a volumecontrol record'driven synchronously with the sound record, means forproducing "from the volume control record electrical currentscorresponding to volume variations recorded thereon, a vacuum tube andcircuit therefor, circuiting connecting the varying electrical currentproduced from the volume control record across the grid and plate ofsaid vacuum tube, where-bya varying plate current corresponding theretoappears in the plate circuit of the tube, means providing a varying gridbias on a tube of the amplifier in accordance with the variations insaid plate current, and means for reproducing sound waves from theelectrical current output of the amplifier.

3. In a system; for reproducing sound waves from a sound record, meansfor driving the sound record, means for producing from the sound recordvarying electrical current waves correspondmg to the sound waves, avacuum tube amplifier or amplifying said current waves, a resistancebetween thefilament and grid of a tube of said amplifier providingnegative bias onsaid grid, 8. volume control record driven synchronouslywith the sound record, means for producing from the volume controlrecord electrical currents corresponding to volume variations recordedthereon, a vacuum tube,

a plate circuit therefor including the biasing negative bias on theamplifier tube and t erefore the amplification of the tube, and meansfor reproducing sound waves from the electrical current output of theamplifier.

4. In a system. for reproducin sound waves from a sound record, means ordriving the sound record, means for producing from the sound recordvaryin electrical waves corresponding to the soun waves, circuitingincluding a vacuum tube amplifier for transmitting said varyingelectrical waves, a vacuum tube in said circuiting including filament,grid, plate and screen grid elements, a volume control record drivensynchronously with the sound record, means for producing from the volumecontrol record varying electrical currents corresponding to volumevariations recorded thereon, a vacuum tube having grid and plateelements, a circuit therefor, circuiting connecting the varyingelectrical current produced from the volume control record across thegrid and plate of the last mentioned vacuum tube, so that acorrespondingly varying plate current appears in the plate circuit ofthe tube, circuiting connecting said plate circuit with the screen gridof the screen grid vacuum tube in such 'a. manner that said varyingplate current controls the amplification of the screen grid tube, andmeans for reproducing sound waves from the electrical current output ofthe amplifier.

5. In a system for reproducing sound waves from a sound record, meansfor driving the sound record, means including a source of light and aphotoelectric cell for producing electrical waves from the sound record,a circuit for transmitting said electrical waves, means for reproducingsound waves from said electrical waves, .a volume control record movedin synchronism with the sound record, means for producing from thevolume control record electrical current waves corres onding to volumevariations recorded -t ereon, a vacuum tube having grid and plateelements and a circuit therefor, circuiting connecting the varyinelectrical current produced from the Y v0 ume control record across thegrid and j platedof said vacuumltllbe, so that a corres n mgyvarym a ecurren a pears 1n 6 t8: plate circu1t of tl ie vacuum tube and cmcui'tmg associating said plate circuit with the hotoelectric cell of thesound record reproducing means so that'the output of said Nphotoelectric cell is controlled in accordance I 10 with the platecurrent variations. c v In witness that I claim the foregoing I.have'hereunto subscribed my name t is 19th day of September 1929.:IAMES R. BALSLEY.

